stdlib: Change the default kernel boot param from "ro" to "rw"

Running workloads likely causes some content to be written to
the disk image, e.g., `m5 readfile`. However, on riscv boards,
the default kernel param specifies the disk image to be read-only.

This change changes this param so that the disk image is
read-write by default.

Change-Id: I414e483ad11d747f34433560e32a8f91a425ce7e
Signed-off-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/65194
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
3 files changed